This invention relates to the field of medical electronics and particularly to an improved device for handling electrical leads having implantable body tissue electrodes.
U.S. Pat. No. 3,737,579 discloses a device or tool for holding an electrical lead during body implantation in such a manner that by rotating the tool the helix-shaped electrode can be screwed into place without imparting torque to the lead along its entire length. The lead or electrode assembly includes three funtionally distinct sections: (1) an implantable, conductive helix-shaped electrode affixed to an insulated boot, (2) a flexible, insulatingly covered conductor, and (3) a plug or connector for connection to a power source. The device or tool for holding this lead disclosed in the above-mentioned patent includes three elements which serve to hold the lead during implantation--a slotted end, a longitudinally extending groove, and a bore extending the length of the tool, and parallel to the groove. The slotted end has straight, uniplanar sides dimensioned to accommodate the boot with enough compression to retain the boot in the slot during the implantation procedure yet permitting removal of the boot from the slot without disturbing the implanted helix. While the boot member has proved satisfactory, some problems have been encountered in retaining the boot in the slot if the boot and/or the slot is wet, especially prior to initially positioning the boot in the slot.
The longitudinally extending groove of the former device accommodates the flexible, insulatingly covered conductor during implantation while the bore receives the connector. Once the helix-shaped electrode is implanted in the body tissue, the lead is disengaged from the tool in three steps; first, removal of the connector from the bore; second, removal of the boot member from the slotted end; and third, removal of the flexible conductor from the groove. The second step is preferably accomplished by an auxiliary tool shaped like a knitting needle which is inserted through the bore until the end of the needle-shaped tool pushes the electrode boot out of the slot. This operation does not, however, simultaneously remove the flexible, insulatingly covered conductor from the groove. Depending upon the tightness of the grip between the outer surface of the flexible conductor and the groove, freeing of the flexible conductor can be a cumbersome task in the surgical environment.
In the present invention, there is provided a device for use in screwing the conductive uninsulated distal end portion of a body implantable electrode assembly into body tissue, said assembly being of the type including a flexible insulated electrical conductor having a proximal end thereof adaptable for connection to a power supply, said device comprising: (1) first means for firmly holding a portion of said electrode assembly near said uninsulated distal end portion thereof, (2) second means adapted to contact an insulated portion of said insulated conductor for releasably holding said conductor to facilitate the screwing of said distal end portion into body tissue and for preventing the transmission of torque to said proximal end of said conductor means when said distal end portion is being screwed into body tissue, and (3) third means communicating with said first and second means whereby said electrode is releasable from said first and second means by means locatable in said third means.
A second or auxiliary device for use in combination with the above-defined primary device is also provided, such auxiliary device including a first portion moveable in the third means of the primary device, a second portion associated with the first portion and moveable in the second means of the primary device, and a third portion moveable into the first means of the primary device whereby movement of the auxiliary device into operative position with respect to the primary device removes the implantable electrode from the primary device. As will be seen hereinafter, this auxiliary device permits the boot-shaped distal end of the lead to be removed from the slotted end of the primary device in the same operation as the flexible, insulatingly covered conductor from the groove of the primary device.